IEC 60909-4 PDF

Buy IEC/TR Ed. Short-circuit currents in three-phase a.c. systems Part 4: Examples for the calculation of short-circuit currents from SAI Global. The results meet requirements of IEC and match the example provided in IEC TR section 6. The IEC standard terminology is used in the user. The International Electrotechnical Commission (IEC) is the leading global IEC TR , Short-circuit currents in three-phase a.c. systems – Part 4.

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IEC TR 60909-4:2000

Factor m for the heat effect of the d. During the initial stage of the short circuit, the negative impedance is approximately equal to the positive-sequence impedance, independent of whether the short circuit is a near-to-generator or a far-from-generator short circuit.

The following features are supported: In this standard it is calculated using a factor m for the time- dependent heat effect of the 60909–4. The transformer correction factor K T for two winding units with or without on-load tap changer LTC is calculated as follows per section 3. RL is the line resistance for a conductor temperature of 20 OC, when calculating the maximum short-circuit currents.

IEC- lire: The IEC collaborates closely with the International Organization for Standardization ISO in accordance with conditions determined by agreement between the two organizations. In special cases the zero-sequence equivalent short-circuit impedance of network feeders may need to be considered, depending on the winding configuration and the starpoint earthing of the transformer.

The initial line-to-earth short-circuit current Iil in figure 3d shall be calculated by: The impedances and z o L of low-voltage and high-voltage cables depend on national techniques and standards and may be taken from 660909-4 or from textbooks or manufacturer’s data.

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Ratings for HV breaker in project file loaded from the library In the equipment short-circuit duty report, comments and text colors provide indication of problem areas. In the equipment short-circuit 60909-44 report, comments and text colors provide indication of problem areas. The resistive component uRrcan be calculated from the total losses PkiTin the windings at the rated current IrT, both referred to the same transformer side see equation 8.

Breaking currents are calculated at 0.

IEC Short-Circuit in EasyPower

Subtransient impedances are used for rotating machines with the impedance correction factors. For other ,values of minimum time delay, linear interpolation between curves is iiec. Q5 This standard meets my needs: The factor K shall, be calculated according to 4.

Ikpis the steady-state short-circuit current of a generator at a three-phase terminal short-circuit. For the calculation of the initial short-circuit currents according to 4. EasyPower applies impedance correction factors in short circuit calculation based on IEC standard. This uec in the case of a far-from-generator short circuit. For simplification, it is permitted to use the same value for as for the three- phase short circuit.

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Synchronous Generator Impedance Correction Factor The synchronous generator impedance correction factor K G for generators without unit transformers is calculated as follows per section 3. The following methods are supported for meshed networks as per section 4. The phase angles displayed are relative to the applied equivalent voltage source being at zero angle. Nominal system voltage, line-to-line r.

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For breaking current you can choose from 0. The symbols represent physical quantities possessing both numerical values and dimensions that are independent of units, provided a consistent unit system is 6090-94, for example the international system of units SI. Figure 1 609909-4 schematically the general course of the short-circuit current in the case of a far-fiom- generator short circuit.

If the highest partial short-circuit current of the power station unit at the high-voltage side of the unit transformer with off-load taps is searched for, choose l-pT. You can enter equipment data and parameters via user friendly interface.

IEC-60909 Short-Circuit in EasyPower

IEC section 6 provides a sample calculation as a benchmark test for software programs to compare. Short-circuit on any bus results in voltage drop in other 6090-94 buses in the system. I librarian researcher I design engineer safety engineer ci Q7 Please assess the standard in the I 660909-4 categories, using testing engineer ci the numbers: Peak current based on method c: The value should be obtained from the manufacturer.

It is only necessary to choose the branches which carry partial short-circuit currents at the nominal voltage corresponding to the short-circuit location and branches with transformers adjacent to the short-circuit location.

Eic JSrT ; t, is the rated transformation ratio of the unit transformer: The short-circuit impedances for electrical equipment are modified using impedance corrections factors that are calculated based on section 3.